1. Field of the Invention
The present invention is directed generally to a coil member for an electromagnetic relay having a delayed response. More particularly, the coil member includes a coil tube for accepting a core as well as two flanges connected thereto at the ends of the coil tube. A winding is applied on the coil tube between the flanges.
2. Description of the Related Art
When a chattering drive signal is applied to relays such as due to poor switches in motor vehicles, there is a risk that quickly responding relays will go along with the chattering signal of these drive switches. This results in the contacts of the relays being repeatedly switched on and off until they remain closed. Such on and off switching leads to greater contact wear and may lead to welding of the contact elements when the switch loads carried by the closed contacts have high currents. If the delayed response of the relay were to be delayed so that the closing of the contacts occurred after the chattering of the drive signal chattering, the problem would be solved, at least in part.
It is already known to achieve a delayed response in a relay by providing a short circuit ring or by providing a solid short-circuit tube of copper. In the known arrangements having these features, however, the usable winding space is reduced by the volume of the short-circuit tube. When a winding space of a fixed size is provided, the excitation power required for the relay is increased.
A coil of the type discussed above which includes a short-circuit tube of copper is disclosed, for example, in German published application No. 15 14 717 and corresponding U.S. Pat. No. 3,421,127, incorporated herein by reference. It is proposed therein that the coil member be formed in multiple parts and be joinable by first slipping a copper tube onto the core tube of the coil member and then connecting the flange to the core tube. This, however, results in not only an increased expense for the parts and manufacturing steps but the winding space is reduced in size by the addition of the copper tube.